An effective strategy for shielding polysulfides and regulating lithium deposition in lithium-sulfur batteries

摘要

The lithium-sulfur (Li-S) battery is an appealing choice for the next-generation high-energy-density energy storage systems. However, side reactions between lithium polysulfides (LiPSs) and Li metal anode cause the growth of Li dendrites, loss of active materials, and safety issues, which severely hinders the practical application of Li-S batteries. Constructing a protection layer on the surface of Li anode is an effective strategy to shield LiPSs and regulate lithium uniform deposition in Li-S batteries. Herein, we design and fabricate a lithiated Nafion protective layer to alleviate the side reactions between LiPSs and the Li anode and guide uniform deposition of Li, in which, their mechanism is investigated. The optimal protective layer effectively protects the Li anode from the detrimental side reactions, which boosts the stability of the Li anode. Li-Li and Li-stainless steel cells with 4 M [S] Li2S8 electrolyte can last for more than 400 cycles and 100 cycles at current density of 1 mA cm(-2). A Li-S full cell also exhibits a high reversible capacity of 791.5 mA h g(-1) after 250 cycles at 0.5 C. This work reveals the vital role of the artificial protective layer in enhancing the stability of the Li anode in Li-S batteries.